Introduction. Acute myocardial infarction (AMI) is a major cause of mortality. The Charlson Comorbidity Index (CCI), widely used to assess comorbidity impact on survival, has yet to be fully evaluated for predicting in-hospital and long-term mortality in AMI patients undergoing coronary angiography. The objective of the study was to evaluate the impact of CCI on mortality in AMI patients undergoing coronary angiography and whether adding CCI to the GRACE 2.0 score improves mortality prediction. Material and methods. The prospective observational study included 712 patients (median age 65, 61% male) with acute MI who underwent coronary angiography within 24 hours. The primary endpoint was in-hospital and 18-month mortality rate. A two-tailed p-value < 0.05 was considered statistically significant for all analyses. Results. The patients were categorized by CCI scores: 0 (n=37), 1 (n=200), 2 (n=256), and ≥3 (n=219). In-hospital and 18-month mortality rates were 5.1% and 12.1%, respectively. In-hospital mortality rates by CCI categories were 0%, 1.0%, 2.0%, and 13.2% (p<0.001), and 18-month mortality rates were 0%, 3.5%, 6.6%, and 28.3% (p<0.001). After adjusting for GRACE 2.0 score, CCI was associated with in-hospital (odds ratio [OR] 1.29, 95% confidence interval [CI]: 1.07–1.57, p<0.001) and 18-month mortality (OR 1.37, 95% CI: 1.20–1.57, p<0.001). CCI showed a strong predictive ability for in-hospital mortality (c-statistic 0.826) and modest performance for 18-month mortality (c-statistic 0.797). Adding CCI to GRACE 2.0 score improved long-term mortality prediction (c-statistic 0.819, net reclassification improvement = –0.154, p=0.015 and integrated discrimination improvement = 0.068, p<0.001). Conclusions. CCI independently predicted in-hospital and 18-month mortality in AMI patients. Incorporating CCI into the GRACE 2.0 score enhanced long-term mortality prediction. © 2025 Elsevier B.V., All rights reserved.